Positioning lights and plants for an indoor cannabis garden

Just like human beings cannot leave without oxygen, plants, on the other hand, cannot survive well without light. This fact also applies to out treasured marijuana plants. Through their leaves, marijuana plants use the light for photosynthesis which transforms into chemical energy needed to grow.

With outdoor growing, this phenomenon works perfectly and in most cases, plants will naturally bend towards the light in a case of deprivation or limit. With the indoor cultivation of marijuana, however, it’s not enough to just shine a bright light on the plant, sit back and relax.

Sometimes it gets so technical and confusing for the new growers forcing some of them to consider falling back. However, to get the best yield from marijuana, the positioning of the grow lights is very important.

Understanding the Plants’ Lighting Needs

First off, you need to understand the light color, intensity and duration of light that your marijuana plants need depending on the stage. Let me give you a little background on light. Light waves come in a spectrum of colors namely blue waves and red. Whereas the Blue waves are smaller and contain more energy, red light waves, on the other hand, are longer with less energy.

This makes the blue lights more favorable for vegetative growth and red lights for the flowering stage. When it comes to the sun, however, it is a full spectrum light and contains all colors and hence appears white.

The intensity of the light also greatly affects the general look of the plants. Plants receiving a low light intensity tends to grow longer and stringy as they stretch in search for sufficient light while plants with a high-intensity are short and bushier with definitely higher yields. Light intensity can be slightly adjusted by changing its distance for the plant.

Therefore, the longer the distance from the plants, the less the light and hence the less the yields while the shorter the distance from the plants, the more intense the light and hence bigger plants.

Ensuring the plant’s access to light

Spacing of the plants

Spacing the plants is one way to ensure that the light fully hits them on all sides. Even with other plants, when they are too compact, most of them will not get a glimpse of the light and hence this will affect the process of photosynthesis.

Therefore, to ensure that every plant gets sufficient light, make sure that there is enough spacing between the plants. It is therefore important that each bud receives a significant amount of light. Uneven distribution of light in an indoor garden will lead to some plants having stunted growth.

Positioning lights and plants for an indoor cannabis garden

Positioning lights and plants for an indoor cannabis garden

Positioning lights

Distance between light and plant

Because of the technicalities sometimes involved, indoor growers fail at determining what distance the light has to be from the plants. If placed too far from the plants, the plants will be deprived of energy and hence will end up stunted. On the other hand, if it is too close, the heat from the lights might just get the plants to dry that they die.

The technicalities even get more complicated when we consider the amount of energy that the different lights emit, to be able to determine at what distance the light should be from the plant. Fortunately for you, here is a simple way to know how far apart the lights have to be from your plant;

Type of light: distance from plants

LED: Very near

Fluorescents: three to four inches

Compact Fluorescents: three inches

Sulphur bulbs: Eighteen inches

Induction Lighting: Fourteen to eighteen inches

Metal halide lights 250 Watts: eight to 12 inches

High-Intensity Discharge Lights:

1000 Watts: Twelve to eighteen inches

600 Watts: Eight to sixteen inches

400 Watts: Eight to sixteen inches

250 Watts (or lower): As close as possible

The easiest way to determine if the heat from the lights will be favorable for your plants is by the use of your hands. If in any case, you feel uncomfortable with your hands placed bellow the light then in the same way your marijuana plants are less likely to thrive in that heat.

Big plants and small plants

In order to allow each plant to get an equal share of the light, it is advisable to position the light to directly hit the smaller plants. This helps to ensure that they are not overshadowed by the bigger plants which might lead to them dying. This way, the small plants are also able to receive the same amount of light like the big plants and hence achieve a uniform growth.

Use reflective materials

The light set up is one of the most expensive investments for an indoor marijuana garden. It is for this reason therefore that preventing light loss through a reflective material is a great way to utilize this resource. When the lights are placed horizontally, it is much easier to maximize light with the introduction of reflectors in the garden.

The light that bounces to the walls can easily be reflected back to the plants if the walls have some sort of reflecting material on it. The best and most commonly used reflectors for indoor gardens are aluminum, both beaten and smooth, Mylar or Panda foil. These materials are highly reflective and help greatly with ensuring that all the light is put to use and that the plants are fully covered. Some farmers have gone as far as painting the walls of the grow room white or using linoleum paneling.

When it comes to reflectors, the placement of the light in the room can affect the amount of light reflected back from the reflector. It is more advisable to place the light closer to the wall than in the middle of the room in order to attain even light. Therefore, make sure that the reflector’s edge is 12 inches away from the wall and 24 inches away from each reflector.


Growing your own marijuana is a wonderful and sometimes challenging experience. It is a great way to celebrate our new found freedom to medicate and enjoy cannabis without having to go through back door deals. With this, you can expand your indoor grow room and be able to get that healthy looking bad you have always wanted.